Responding to RFA-DA-09-007, we propose to conduct a randomized clinical trial to determine the clinical effectiveness, moderators and mechanisms of change, and economic impact of an integrative, family-based intervention that concurrently targets changes in HIV/STD-associated risk behaviors, drug abuse, delinquency, arrest and mental health outcomes for juvenile offenders committed to a juvenile justice day treatment program. 250 sexually active youths with documented substance use disorders enrolled in a school-based, juvenile justice day treatment facility will comprise the study sample. Eligible youths will be randomized to the experimental intervention. Day Treatment Multidimensional Family Therapy-HIV (DT-MDFT-HIV) or Day Treatment Services as Usual (DT-SAU). This study is distinguished by its setting, a juvenile justice administered day treatment program, and by the experimental intervention's promise in simultaneously reducing multiple adolescent problems-HIV-associated risk behaviors, drug abuse, and criminal behavior. Interventions targeting each of these problem areas are typically delivered separately, perpetuating well documented problems of service fragmentation in juvenile justice, addictions treatment, and health systems. Given the empirically-established relationships among high risk sex, drug abuse, and delinquency; the need for new service delivery systems that can efficiently deliver comprehensive interventions to multiply impaired youths; and the need for innovative juvenile justice alternatives to residential placement and incarceration, the proposed study has the potential to successfully address an urgent public health, public safety, and research priority. The study has four aims: (1) Clinical Outcomes - to compare the effects of the family-based and the group-based interventions on HIV risk/STD rates, drug use, delinquency and mental health outcomes, (2) Moderators of Outcome - to determine if the more comprehensive and integrated experimental intervention, MDFT-HIV, is more effective with more severely impaired youths, (3) Mediators of Outcome - to determine if hypothesized mechanisms of action of MDFT-HIV mediated changes in outcomes over time, and (4) Economic Analyses - to evaluate and compare the economic costs, benefits, and cost effectiveness to society and to the juvenile justice system of MDFT-HIV and SAU. A multiple time point (intake, 3, 6, 12, and 24 month follow-up), multiple domain and method assessment approach and latent growth curve modeling techniques will be used to examine study hypotheses regarding adolescent and family change over time. The study has significant potential to improve interventions and service delivery systems by providing new knowledge about effective and cost-efficient interventions for drug abusing juvenile offenders at high risk for HIV infection.